14  Unit 4: Climate Change - Unit Opening

How do natural factors contribute to changes in Earth’s temperature?

15 Anchor Phenomenon

15.1 🌍 Earth’s Temperature Is Rising

Earth’s temperature is rising, reversing the cooling trend that occurred over the past 2,000 years, putting millions of people in harm’s way, yet the public is not convinced of the risks.

15.1.1 Essential Questions:

• How do natural factors contribute to changes in Earth’s temperature?
• What are 99.9% of climate scientists seeing in historical climate data that makes them so sure humans are the cause of climate change today?
• Why does it matter?

16 The Reality of Climate Change

16.1 Global Temperature Trends

Let’s examine how Earth’s temperature has changed over time using real data.

Plot = require("@observablehq/plot")

// Temperature anomaly data (NASA GISTEMP simplified)
tempData = [
  {year: 1880, anomaly: -0.16}, {year: 1890, anomaly: -0.33},
  {year: 1900, anomaly: -0.08}, {year: 1910, anomaly: -0.42},
  {year: 1920, anomaly: -0.25}, {year: 1930, anomaly: -0.14},
  {year: 1940, anomaly: 0.12}, {year: 1950, anomaly: -0.17},
  {year: 1960, anomaly: -0.01}, {year: 1970, anomaly: -0.01},
  {year: 1980, anomaly: 0.26}, {year: 1990, anomaly: 0.45},
  {year: 2000, anomaly: 0.42}, {year: 2010, anomaly: 0.72},
  {year: 2020, anomaly: 1.02}, {year: 2024, anomaly: 1.29}
]

viewof yearRange = Inputs.range([1880, 2024], {
  step: 10,
  value: 2024,
  label: "Explore data up to year:"
})

filteredData = tempData.filter(d => d.year <= yearRange)

Plot.plot({
  title: "Global Temperature Anomaly (°C relative to 1951-1980 average)",
  width: 700,
  height: 400,
  y: {label: "Temperature Anomaly (°C)", domain: [-0.6, 1.5]},
  x: {label: "Year"},
  marks: [
    Plot.ruleY([0], {stroke: "#ccc", strokeDasharray: "4,4"}),
    Plot.line(filteredData, {x: "year", y: "anomaly", stroke: "steelblue", strokeWidth: 2}),
    Plot.dot(filteredData, {x: "year", y: "anomaly", fill: d => d.anomaly > 0 ? "red" : "blue", r: 5}),
    Plot.text(filteredData.slice(-1), {x: "year", y: "anomaly", text: d => `${d.anomaly}°C`, dy: -15, fontSize: 14, fontWeight: "bold"})
  ]
})

16.1.1 ✅ Check Your Understanding

1. What pattern do you observe in the temperature data?
2. Around what year did temperatures begin consistently rising above the baseline?
3. How much warmer is Earth today compared to the 1880s?

16.2 NASA Climate Vital Signs Widget

Explore real-time climate data from NASA:

16.3 Climate Displacement Data

Millions of people have already been displaced due to climate-related events.

displacementData = [
  {year: 2018, displaced: 17.2, type: "Weather-related"},
  {year: 2019, displaced: 24.9, type: "Weather-related"},
  {year: 2020, displaced: 30.0, type: "Weather-related"},
  {year: 2021, displaced: 23.7, type: "Weather-related"},
  {year: 2022, displaced: 32.6, type: "Weather-related"},
  {year: 2023, displaced: 26.4, type: "Weather-related"}
]

Plot.plot({
  title: "People Displaced by Weather-Related Disasters (Millions)",
  width: 600,
  height: 350,
  x: {label: "Year", tickFormat: d => d.toString()},
  y: {label: "People Displaced (Millions)", domain: [0, 40]},
  marks: [
    Plot.barY(displacementData, {x: "year", y: "displaced", fill: "#e74c3c"}),
    Plot.text(displacementData, {x: "year", y: "displaced", text: d => d.displaced + "M", dy: -10, fontSize: 11})
  ]
})

17 Scientific Consensus

17.1 What Do Scientists Say?

consensusData = [
  {group: "Climate Scientists", agree: 99.9, disagree: 0.1},
  {group: "General Public (US)", agree: 57, disagree: 43}
]

99.9%

of climate scientists agree humans are causing climate change

57%

of the US public believes humans are the primary cause

17.1.1 🤔 Driving Question

Why is there such a large gap between scientific consensus and public perception? What evidence convinces scientists that humans are causing climate change?

18 The 2,000-Year Cooling Trend

18.1 Interactive: Long-Term Temperature Record

Before recent warming, Earth had been gradually cooling for about 2,000 years.

longTermData = [
  {year: 0, temp: 0.1}, {year: 200, temp: 0.05},
  {year: 400, temp: -0.1}, {year: 600, temp: -0.15},
  {year: 800, temp: -0.05}, {year: 1000, temp: 0.05},
  {year: 1200, temp: -0.1}, {year: 1400, temp: -0.3},
  {year: 1600, temp: -0.4}, {year: 1700, temp: -0.35},
  {year: 1800, temp: -0.3}, {year: 1850, temp: -0.25},
  {year: 1900, temp: -0.2}, {year: 1950, temp: -0.05},
  {year: 1980, temp: 0.15}, {year: 2000, temp: 0.4},
  {year: 2020, temp: 1.0}
]

Plot.plot({
  title: "2,000 Years of Global Temperature Change",
  subtitle: "Temperature anomaly relative to 1961-1990 average",
  width: 700,
  height: 400,
  x: {label: "Year (CE)", domain: [0, 2025]},
  y: {label: "Temperature Anomaly (°C)", domain: [-0.6, 1.2]},
  marks: [
    Plot.ruleY([0], {stroke: "#999", strokeDasharray: "4,4"}),
    Plot.areaY(longTermData.filter(d => d.year <= 1850), {x: "year", y: "temp", fill: "#3498db", fillOpacity: 0.3}),
    Plot.areaY(longTermData.filter(d => d.year >= 1850), {x: "year", y: "temp", fill: "#e74c3c", fillOpacity: 0.3}),
    Plot.line(longTermData, {x: "year", y: "temp", stroke: "#2c3e50", strokeWidth: 2}),
    Plot.text([{x: 900, y: -0.45, text: "Natural Cooling Trend"}], {x: "x", y: "y", text: "text", fill: "#3498db", fontSize: 12}),
    Plot.text([{x: 1950, y: 0.7, text: "Industrial Era Warming"}], {x: "x", y: "y", text: "text", fill: "#e74c3c", fontSize: 12})
  ]
})

18.1.1 💡 Key Ideas from the Unit Opening

• Over the past 2,000 years, Earth had been cooling, until about 200 years ago
• Millions of people have been displaced because of weather-related incidents
• The scientific consensus is that humans are causing climate change and that it is a big deal
• The public is less certain that humans are causing climate change

19 Student Questions

Based on what you’ve observed, what questions do you have?

19.0.1 Questions to Investigate in This Unit:

1. Why was Earth’s temperature cooling before but is rising now?
2. Why are people being displaced by climate factors?
3. Why are scientists sure that humans are causing climate change?
4. Has the climate ever changed before, and if so, how did it impact populations?
5. How will climate change affect people now and in the future?
6. Why are scientists so sure that climate change is a big deal?

20 Performance Task Preview

20.1 📋 Your Mission

Throughout this unit, you will analyze and interpret data related to changes in climate in the past in order to:

1. Understand how we are so confident humans are the cause of current climate change
2. Communicate this information to educate others in your community about the risks
3. Predict how climate factors will be affected in the future
4. Explain how populations will be impacted

By the end of this unit, you will create a communication piece for someone in your community that explains: - Why scientists are certain humans are causing climate change - How climate factors will be affected - How populations will be impacted

21 Initial Ideas Activity

21.1 What natural factors might cause climate change?

Brainstorm: Natural Climate Factors

Before we investigate, record your initial ideas about what natural factors could have caused changes in climate in the past:

• Changes in the Sun's energy output
• Volcanic eruptions
• Changes in Earth's orbit
• Ocean current changes
• What else?

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21.2 📝 Unit Opening Quiz

Question 1: Based on the temperature data, approximately how much has global temperature increased since 1880? - A) 0.5°C - B) 1.0°C - C) 1.5°C - D) 2.0°C

Question 2: What percentage of climate scientists agree that humans are causing climate change? - A) About 57% - B) About 75% - C) About 90% - D) About 99.9%

Question 3: Before approximately 200 years ago, Earth’s temperature had been: - A) Rapidly warming - B) Staying constant - C) Gradually cooling - D) Fluctuating wildly

Question 4: Why is the gap between scientific consensus and public perception important to address? - A) It doesn’t matter what the public thinks - B) Scientists might be wrong - C) Public support is needed for climate action - D) The public knows more than scientists

Question 5: What is the anchor phenomenon for this unit? - A) Ice ages occur every 100,000 years - B) The Sun’s output varies over time - C) Earth’s temperature is rising, reversing a 2,000-year cooling trend - D) Volcanoes cause climate change

Answers: 1-C, 2-D, 3-C, 4-C, 5-C